The invention relates to a dentistry hand piece, wherein a rotation of a drive motor is converted into an oscillation of a receiving part for a dentistry tool.
Such a hand piece is known, for example, from U.S. Pat. No. 5,133,661. In this straight hand piece, an eccentric driven by a rotating drive shaft is provided, which causes a receiving part for a tool to oscillate. The receiving part arranged in the shaft of the hand piece, in the longitudinal direction of the hand piece, is provided at its forward end with a thread into which the tool can be screwed. Instead of a tool, an attachment head can also be screwed into the thread, which then oscillates as a whole in operation and which is provided with a chuck for inserting a vibrating tool.
Modifications must be made in order to obtain suitably practical ergonomics of the hand piece, so that the places to be treated on the teeth can be reached with the tip of the tool fitted into the receiving part or in the attachment head. On one hand, the tools which can be screwed into the receiving part are bent, wherein their tips are at an angle to the longitudinal axis of the hand piece. On the other hand, the chuck of the attachment head which can be screwed into the receiving part is arranged at an angle to the longitudinal axis of the hand piece. However, when this is done the plane of oscillation of the tool is inclined with respect to the forward area of the tool, and the movement of the tip of the tool has a disadvantageous "knocking" component (component of movement directed perpendicular to the surface of the tooth) during various types of treatment when it is placed on the tooth.